Abstract: Objective To investigate the apoptosis and cell growth inhibition in vitro effects of recombination onconase (rONC) on rat hepatoma cell RH-35. Methods After RH-35 cell in vitro were treated with various concentrations of rONC. Cel1 proliferation were determined by the SRB method and the bioactivities of these cell were detected by Hoechst33258. The effect of rONC on cell cycle were detected by flow cytometry assay. The expression levels of cell proliferation related genes and proteins after RH-35 cell treated with rONC were detected by qRT-PCR and Western blot. Results The proliferation of RH-35 cell were significantly inhibited after treated with rONC for 24 hours and this inhibitory action was positive correlated with time and dose-dependent (P<0.05) . The value of IC50 was 7.38 ?mol/L. The nucleus appeared some characteristic of apoptosis after RH-35 cell treated with rONC .The proportion of cells in G0/G1 phases remarkably rise after 24 h treatment with rONC, rONC could down-regulate the expression level of PCNA, CCNA2, BCL-2 and up-regulate BAX gene levels and protein levels. Conclusion rONC could inhibit the growth and induce apoptosis of RH-35 cell in vitro due to the down-regulated expression of PCNA, CCNA2, BCL-2 and up-regulated expression of BAX.

Key words: Key words: recombination onconase, rat hepatoma cell line RH-35, growth inhibition, apoptosis